1. Field of the Invention
The invention relates to an industrial truck, in particular a forward-control counterweight fork-lift truck, having a liftable and tiltable load-lifting device, a traction drive, operating drives for movement of the load-lifting device, and a steering drive.
2. Technical Considerations
In the case of known industrial trucks, the operator has to estimate the weight of the load goods to be lifted (lifting load) and the height to which the load goods are lifted (lifting height). On the basis of this, the driving speed and the turning radius of the industrial truck must be set such that there is no tipping of the industrial truck to the front or to the side. This demanding task may be too much for the operator and, thus, when the load-bearing capacity of the industrial truck is exceeded or in the event of driving maneuvers which are not adapted to the current lifting load and lifting height, tipping accidents may result involving severe injury or death to the operator or nearby people associated with a high level of damage to property. There has, therefore, been no shortage of thought given to creating suitable safety precautions for preventing accidents involving industrial trucks.
DE 29 09 667 C3, for example, describes a generic industrial truck with which there is intervention in the traction drive, depending on the steering angle, the lifting height, and the load torque, and, in the process, the driving speed and, if necessary, also the (electromotive) braking deceleration is limited. This takes place by overriding the desired values predetermined by the operator, using correction signals from the control device.
The subject matter of EP 0 343 839 B1 is an industrial truck in which the driving speed is limited depending on the lifting load, the lifting height, the steering angle, the direction of travel, and the position of the center of gravity of the vehicle. In addition, provision is also made for limiting the acceleration of the industrial truck depending on the lifting height.
EP 1 078 878 A1 discloses the concept of limiting the tilting speed of an industrial truck lifting mast depending on the lifting load and the lifting height.
Finally, EP 1 019 315 B1 discloses an industrial truck in which the driving speed is limited depending on the lifting load and the tilting angle, and a higher lowering speed without a load is made possible.
One common factor with all of the proposals is the fact that in each case only partial aspects of the operating behavior of the industrial truck are taken into consideration, and, as a result, operating states remain in which there is a considerable risk of tipping.
The present invention is, therefore, based on the object of providing an industrial truck of the general type mentioned above but which has good tipping stability in, if possible, all driving states which are critical in terms of tipping.